The House Swift is a small (15 cm) blackish
swift with a white throat and rump and a slightly notched tail. The Taiwan
subspecies kuntzi is described as having a more heavily streaked rump
than mainland races, but differences are unlikely to be visible in the
field.

The House Swift feeds on flying insects
such as wasps, bees and flies which it catches on the wing, usually at a
great height. It often feeds in large flocks and is usually very vocal,
giving trills of rapidly-repeated, high-pitched screaming notes. It roosts
by hanging from cliffs, bridges and under the eaves of buildings, sometimes
in large flocks. Its nest is a large, loose hemispherical structure of
plant material and feathers glued together with saliva. It may be placed on
a cliff, a bridge or under the eave of a building.

The House Swift is a common resident of
Taiwan from the plains to mid-elevation mountain areas, and sometimes at
higher elevations.

References: Handbook of
Birds of the World Vol. 5; A Field Guide to the Birds of China (Mackinnon
and Phillipps); 100 Common Birds of Taiwan (Wild Bird Society of Taipei); N.
J. Collar, “Endemic
subspecies of Taiwan birds—first impressions”, in Birding ASIA, Number 2,
December 2004